Method of reducing near-end crosstalk in an MxU networking architecture

ABSTRACT

HPNA MxU network for an MxU, the MxU including a plurality of HPNA LANs, each of the HPNA LANs operating according to a synchronous communication specification, each of the HPNA LANs including a plurality of nodes, one of the nodes within each HPNA LAN being a gateway node, a selected one of the nodes within each HPNA LAN being defined a LAN-master node, each HPNA LAN being coupled with a WAN via the respective gateway node, wherein communication lines within the HPNA LANs, directly coupled with the gateway nodes, are at least partially bound together, wherein the transmission direction within a selected HPNA LAN, by the respective gateway node, is defined downstream, wherein the transmission direction within a selected HPNA LAN, to the respective gateway node, is defined upstream, wherein the transmission direction within a selected HPNA LAN, between nodes other than the respective gateway nodes, is defined HN, wherein the LAN-master nodes allow the gateway nodes to transmit downstream signals during at least one time slot, and wherein the LAN-master nodes allow the nodes other than the gateway nodes to transmit upstream signals or HN signals, during at least another timeslot.

FIELD OF THE DISCLOSED TECHNIQUE

The disclosed technique relates to communication networks in general,and to methods and systems for reducing near-end crosstalk in MxUnetworks, in particular.

BACKGROUND OF THE DISCLOSED TECHNIQUE

MxU networking architecture is known in the art and is used to providecommunication services to a site (e.g., an apartment building) whichincludes a plurality of substantially independent sections (e.g., aplurality of apartments), each associated with a different subscriber.In general, the MxU networking architecture defines a separate localarea network (LAN) for each of the sections.

MxU networks which are based Home Phoneline Networking Alliance (HPNA),use the telephone lines of the telephone wire network, already installedin the MxU. Each of the LANs includes the telephone wires which areassociated with a selected section (e.g., apartment) and a plurality ofHPNA nodes coupled with the telephone outlets. Telephone network voicecommunication and data communication services can be usedsimultaneously, using a technique known as frequency divisionmultiplexing (FDM). Accordingly, data signals are transmitted using adifferent (higher) frequency than voice data signals, whereby thesesignals, can be separated using a frequency splitter.

A common problem in communication networks in general and MxU networksin particular, is interference between signals transmitted on adjacentcommunication lines, also known as crosstalk. Crosstalk is especiallyproblematic when it is induced by a transmitter, transmitting over acommunication line, to a nearby receiver which receives signals from anadjacent communication line. This type of crosstalk is known as near-endcrosstalk (NEXT).

Methods and systems for reducing crosstalk in a network are known in theart. One conventional method for reducing NEXT is to use frequencydivision to separate between potentially interfering signals.Accordingly, signals transmitted in the upstream direction (i.e., fromthe user to the Central Office of the service provider) are transmittedusing a different frequency than the signals transmitted in thedownstream direction. For example, ADSL uses a lower frequency band forupstream communication and a higher frequency band for downstreamcommunication.

Time division multiplexing (TDM) is a method, known in the art forpreventing crosstalk between two different services (e.g., ISDN andADSL). In a network using TDM, timeslots are defined for specific typesof transmission and reception. For example, a certain timeslot may beallocated for transmission by one service, and a second timeslot foranother service, whereby these transmissions do not interfere therebetween.

U.S. Pat. No. 5,991,311, entitled “Time-Multiplexed Transmission onDigital-Subscriber Lines Synchronized to Existing TCM-ISDN for ReducedCross-Talk”, issued to Long et al., is directed to a data-service-line(DSL) system for installing together with an existing IntegratedServices Digital Network (ISDN) system, wherein the ISDN system usestime-compression multiplexing (TCM). The DSL system also uses TCM. Thisenables synchronizing the TCM-DSL system and the TCM-ISDN system, usinga clock. All of the TCM-ISDN line cards and the TCM-DSL line cards ofthe central office, transmit during a first time window, and receiveduring a second time window.

Reference is now made to FIGS. 1A and 1B. FIGS. 1A and 1B schematicallyillustrate an apartment building network, generally referenced 10, whichis known in the art. FIGS. 1A and 1B show a first and second example ofNEXT in an MxU network, respectively. It is noted that FIGS. 1A and 1Bare not drawn to scale.

With reference to FIG. 1A, apartment building network 10 includesintra-apartment networks APT₁ (referenced 12 ₁), APT₂ (referenced 12 ₂)and APT_(N) (referenced 12 _(N)), gateways G₁ (referenced 22 ₁), G₂(referenced 22 ₂) and G_(N) (referenced 22 _(N)), and telephonetwisted-pair wires 24 ₁, 24 ₂ and 24 _(N). A telephone wire binder 18runs from a basement 14 of the apartment building, to the vicinity ofintra-apartment networks 12 ₁, 12 ₂ and 12 _(N). A platform 16 islocated in basement 14. Gateways 22 ₁, 22 ₂ and 22 _(N) are mounted onplatform 16. A broadband source 20 couples each of gateways 22 ₁, 22 ₂and 22 _(N) with a wide area network (WAN) such as the Internet, via abroadband link such as xDSL, cable, fiber-optic, satellite, LocalMultipoint Distribution System (LMDS), and the like.

Each of intra-apartment networks 12 ₁, 12 ₂ and 12 _(N) includes severalnetwork nodes (not shown), as shall be described in further detail withreference to FIG. 1C. Each one of gateways 22 ₁, 22 ₂ and 22 _(N) iscoupled with a respective one of intra-apartment networks 12 ₁, 12 ₂ and12 _(N), via respective telephone wires 24 ₁, 24 ₂ and 24 _(N). Eachcombination of one of the gateways 22 ₁, 22 ₂ and 22 _(N), therespective one of the telephone wires 24 ₁, 24 ₂ and 24 _(N), and therespective one of intra-apartment networks 12 ₁, 12 ₂ and 12 _(N),together form a respective one of local-area networks (LANs) 15 ₁, 15 ₂and 15 _(N). Telephone wires 24 ₁, 24 ₂ and 24 _(N) are bound togetherin binder 18.

Gateway 22 ₁ transmits a data signal 26 to intra-apartment network 12 ₁.Simultaneously, intra-apartment network 12 ₂ transmits another datasignal 28 to gateway 22 ₂. In a region 32, located in the vicinity ofplatform 16, an electrical disturbance 30, associated with data signal26 (from telephone wire 24 ₁), is induced in telephone wire 24 ₂,causing an interference in data signal 28.

It is noted that conventionally, the distance between intra-apartmentnetwork 12 ₂ and region 32 is significantly greater than the distancebetween gateway 22 ₁ and region 32. Therefore, data signal 28 undergoesa significantly greater attenuation than data signal 26, before thesedata signals reach region 32, and hence, electrical disturbance 30 maycause a significant interference in data signal 28. This effect is knownas near-end crosstalk (NEXT). It is noted that the transfer ofdisturbance 30 from telephone wire 24 ₁ to telephone wire 24 ₂ is acumulative effect, which takes place all along wires 24 ₁ and 24 ₂, witha primary contribution occurring in region 32.

With reference to FIG. 1B, gateway 22 ₁ transmits a data signal 50 tointra-apartment network 12 ₁. Simultaneously, intra-apartment network 12₂ transmits another data signal 52 to gateway 22 ₂. In a region 56,located in the vicinity of intra-apartment networks 12 ₁ and 12 ₂, anelectrical disturbance 54, associated with data signal 52 (fromtelephone wire 24 ₂), is induced in telephone wire 24 ₁, causing aninterference in data signal 50.

It is noted that conventionally, the distance between gateway 22 ₁ andregion 56 is significantly greater than the distance betweenintra-apartment network 12 ₁ and region 56. Therefore, data signal 50undergoes a significantly greater attenuation than data signal 52,before these data signals reach region 56, and hence, electricaldisturbance 54 may cause a significant interference in data signal 50.

Reference is further made to FIG. 1C, which is an illustration in detailof intra-apartment networks 12 ₁ and 12 ₂ of apartment building network10 (FIGS. 1A and 1B) and a portion of the binder 18. FIG. 1C shows athird example of NEXT. It is noted that FIG. 1C is not drawn to scale.

Intra-apartment network 12 ₁ includes network nodes 80 ₁, 80 ₂ and 80 ₃.Nodes 80 ₁, 80 ₂ and 80 ₃ are coupled there between via telephone wire24 ₁. Intra-apartment network 12 ₂ includes nodes 82 ₁ and 82 ₂. Nodes82 ₁ and 82 ₂ are coupled there between via telephone wire 24 ₂.

Gateway 22 ₂ (FIG. 1A) transmits a data signal 86, through telephonewire 24 ₁, toward intra-apartment network 12 ₂. Simultaneously, node 80₁ transmits another data signal 88 toward node 80 ₂.

It is noted that conventionally, data signal 88 includes a header withsource and target attributes. All of the nodes of LAN 15 ₁ (FIG. 1A)receive data signal 88, but only the target node, which is specified inthe source-target attributes (i.e., node 80 ₂) addresses and decodes thedata signal. It is noted that in the description that follows and theaccompanying drawings, except for the present example, data signals areonly shown on their path to their intended receiving node.

Data signal 88 passes through telephone wire 24 ₁ toward binder 18. In aregion 84 in the vicinity of intra-apartment networks 12 ₁ and 12 ₂, anelectrical disturbance 92, associated with data signal 88 (fromtelephone wire 24 ₁), is induced in telephone wire 24 ₂, causing aninterference in data signal 86. Similarly as in the example set forth inFIGS. 1A and 1B, electrical disturbance 92 may cause a significantinterference in data signal 86.

SUMMARY OF THE DISCLOSED TECHNIQUE

It is an object of the disclosed technique to provide a novel HPNA MxUnetwork architecture, which reduces NEXT and which overcomes thedisadvantages of the prior art.

In accordance with the disclosed technique, there is thus provided anHPNA MxU network for an MxU, the MxU network comprising a plurality ofHPNA LANs. Each of the HPNA LANs operates according to a synchronouscommunication specification. Each of the HPNA LANs comprises a pluralityof nodes, one of the nodes being a gateway node, and a selected one ofthe nodes being defined a LAN-master node. Each of the HPNA LANs iscoupled with a WAN, via the respective gateway node. Communication lineswithin the HPNA LANs, directly coupled with the gateway nodes, are atleast partially bound together thereby susceptible to electromagneticinterference there between. The transmission direction within a selectedHPNA LAN by the respective gateway node is defined downstream. Thetransmission direction within a selected HPNA LAN to the respectivegateway node is defined upstream. The transmission direction within aselected HPNA LAN between nodes other than the respective gateway nodes,is defined HN. The LAN-master nodes allow the gateway nodes to transmitdownstream signals during at least one timeslot, and upstream signalsduring at least another timeslot.

In accordance with another aspect of the disclosed technique, for atleast one of the LANs, the respective gateway node is integrated withthe respective LAN-master node. In accordance with a further aspect ofthe disclosed technique, the MxU network further includes asynchronizer, synchronizing the LAN-master nodes according to thetimeslots.

In accordance with another aspect of the disclosed technique, each ofthe LANs operates according to a single timeslot scheme, simultaneously.In accordance with a further aspect of the disclosed technique, thetimeslot scheme includes a downstream timeslot, allocated fortransmission of downstream data signals, and an upstream+HN timeslot,allocated for transmission of upstream and HN data signals.

In accordance with another aspect of the disclosed technique, there isprovided a method of reducing NEXT in an HPNA MxU network. The networkincludes a plurality of LANs. Each of the LANs includes a LAN-masternode. The method includes the procedures of synchronizing the HPNA MxUnetwork according to a timeslot scheme, which includes a plurality oftimeslots, and during each of the timeslots, transmitting data signalsof a selected type respective of the timeslot.

According to a further aspect of the disclosed technique, there isprovided a synchronizer for synchronizing a plurality of HPNA MxUnetwork LAN-masters there between. The synchronizer includes means forcoupling with the LAN-masters, means for allocating timeslots to theLAN-masters, and means for timing the timeslots. The timeslots determinewhen each of a plurality of nodes of the HPNA MxU network are enabled totransmit upstream, downstream and HN data signals.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed technique will be understood and appreciated more fullyfrom the following detailed description taken in conjunction with thedrawings in which:

FIG. 1A is a schematic illustration of an apartment building networkwhich is known in the art, showing a first example of NEXT;

FIG. 1B is a schematic illustration of the apartment building network ofFIG. 1A, showing a second example of NEXT;

FIG. 1C is an illustration in detail of two of the intra-apartmentnetworks of the apartment building of FIGS. 1A and 1B and a portion ofthe binder, showing a third example of NEXT;

FIG. 2 is a schematic illustration of an MxU network, constructed andoperative in accordance with an embodiment of the disclosed technique;

FIG. 3 is a schematic illustration of an MxU network, constructed andoperative in accordance with another embodiment of the disclosedtechnique;

FIG. 4 is a schematic illustration of an apartment building network,constructed and operative in accordance with a further embodiment of thedisclosed technique;

FIG. 5A is a schematic illustration of a timeslot scheme sequence,constructed in accordance with another embodiment of the disclosedtechnique;

FIG. 5B is a schematic illustration of a timeslot scheme sequence,constructed in accordance with a further embodiment of the disclosedtechnique;

FIG. 5C is a schematic illustration of a timeslot scheme, constructed inaccordance with another embodiment of the disclosed technique;

FIG. 6A is an illustration in detail of two of the intra-apartmentnetworks of the MxU network of FIG. 2, and a portion of the binder, at afirst mode of the MxU network, in accordance with a further embodimentof the disclosed technique;

FIG. 6B is an illustration in detail of two of the intra-apartmentnetworks of the MxU FIG. 2, and a portion of the binder, at a secondmode of the MxU network, in accordance with another embodiment of thedisclosed technique;

FIG. 6C is an illustration in detail of two of the intra-apartmentnetworks of the MxU FIG. 2, and a portion of the binder, at a third modeof the MxU network, in accordance with a further embodiment of thedisclosed technique, and

-   -   FIG. 7 is a schematic illustration of a method for reducing NEXT        in an MxU network, operative in accordance with another        embodiment of the disclosed technique.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The disclosed technique overcomes the disadvantages of the prior art byproviding a synchronous MxU network, which assigns different timeslotsfor upstream and downstream communication.

In the description that follows, the terms MDU (multi-dwelling unit),MTU (multi-tenant unit), MCU (multi-company unit), MHU(multi-hospitality unit), MPU (multi-public unit), MEU (multi-embeddedunit), are generally termed MxU. An MxU may be an apartment building, acondominium complex, a hotel, a motel, a resort, an office building, anindustrial park, a college or university campus dormitory, a hospital,an airport, a train station, a convention center, a shopping mall, anairplane, a ship, and the like.

Reference is now made to FIG. 2, which is a schematic illustration of anMxU network, generally referenced 100, constructed and operative inaccordance with an embodiment of the disclosed technique. It is notedthat FIG. 2 is not drawn to scale. In the present example, MxU network100 is an apartment building network. It is noted, however, that thedisclosed technique is applicable for any type of MxU network.

Apartment building network 100 includes intra-apartment networks APT₁(referenced 112 ₁), APT₂ (referenced 112 ₂) and APT_(N) (referenced 112_(N)), gateways G₁ (referenced 122 ₁), G₂ (referenced 122 ₂) and G_(N)(referenced 122 _(N)), and telephone wires 124 ₁, 124 ₂ and 124 _(N). Atelephone wire binder 118 runs from a basement 114 of the apartmentbuilding, to the vicinity of intra-apartment networks 112 ₁, 112 ₂ and112 _(N). A platform 116 and a synchronizer 126, are located incommunication room 114. Gateways G₁, G₂, and G_(N), referenced 122 ₁,122 ₂ and 122 _(N), respectively, are mounted on platform 116. Abroadband source 120 couples gateways 122 ₁, 122 ₂ and 122 _(N) with awide area network (WAN) such as xDSL, cable, fiber-optic, satellite,Local Multipoint Distribution System (LMDS), and the like. Synchronizer126 is coupled with gateways 122 ₁, 122 ₂ and 122 _(N).

In the present example, communication room 114 is a basement. It isnoted, however, that communication room 114 may any physical spacehousing the gateways of the network, such as a basement, a cupboard, acabinet, and the like.

Each of telephone wires 124 ₁, 124 ₂ and 124 _(N) is a twisted-pairwire. Telephone wires 124 ₁, 124 ₂ and 124 _(N) are also known as PlainOld Telephone Service lines (POTS lines). Telephone wires 124 ₁, 124 ₂and 124 _(N) are bound together in binder 118.

Platform 116 provides access to gateways 122 ₁, 122 ₂ and 122 _(N), bymultiplexing the broadband source 120. It is noted that platform 116 mayfurther provide other functions to gateways 122 ₁, 122 ₂ and 122 _(N),such as routing, switching, dynamic IP address assignment, voice access,power, and the like. For example, platform 116 may be a DigitalSubscriber Line Access Multiplexer (DSLAM), a Next Generation DigitalLoop Carrier (NGDLC), and the like.

Each of intra-apartment networks 112 ₁, 112 ₂ and 112 _(N) includesseveral network nodes (not shown), as shall be described in furtherdetail with reference to FIGS. 6A and 6B. Each combination of one of thegateways 122 ₁, 122 ₂ and 122 _(N), the respective one of the telephonewires 124 ₁, 124 ₂ and 124 _(N), and the respective one ofintra-apartment networks 112 ₁, 112 ₂ and 112 _(N), together form arespective one of local-area networks (LANs) 115 ₁, 115 ₂ and 115 _(N).

Data signals transmitted from one of the gateways 122 ₁, 122 ₂ or 122_(N), to the respective intra-apartment network, are known as downstreamdata signals. Data signals transmitted from one of the intra-apartmentnetworks 112 ₁, 112 ₂ and 112 _(N), to the respective gateway, are knownas upstream data signals. Data signals transmitted and received withinone of the intra-apartment networks, are known as home networking (HN)data signals.

Each of gateways 122 ₁, 122 ₂ and 122 _(N) operates as a master node ofthe respective one of LANs 115 ₁, 115 ₂ and 115 _(N) (i.e., each gatewayis a LAN-master). In other words, each gateway enables or disables thenodes in the respective LAN to transmit data signals. Synchronizer 126synchronizes the gateways 122 ₁, 122 ₂ and 122 _(N), so that LANs 115 ₁,115 ₂ and 115 _(N), transmit upstream, downstream and HN data signals insynchrony, as shall be described in further detail with reference toFIGS. 5A and 5B.

It is noted that synchronizer 126 may generally be coupled with gateways122 ₁, 122 ₂ and 122 _(N) via wired or wireless connections. It isfurther noted that synchronizer 126 may generally be located in variouslocations inside or outside of basement 114, and inside the apartmentbuilding or at a remote location.

Reference is now made to FIG. 3, which is a schematic illustration of anapartment building network, generally referenced 140, constructed andoperative in accordance with another embodiment of the disclosedtechnique. According to the architecture of network 140, thesynchronizer is incorporated within one of the LAN-masters, whereby thisLAN-master operates as a master relative to the other LAN-masters of thenetwork.

Apartment building network 140 includes intra-apartment networks APT₁(referenced 152 ₁), APT₂ (referenced 152 ₂) and APT_(N) (referenced 152_(N)), gateways G₁ (referenced 162 ₁), G₂ (referenced 162 ₂) and G_(N)(referenced 162 _(N)), and telephone wires 164 ₁, 164 ₂ and 164 _(N). Atelephone wire binder 158 runs from a basement 154 to the vicinity ofintra-apartment networks 152 ₁, 152 ₂ and 152 ₃. Gateways 162 ₁, 162 ₂and 162 _(N) are mounted on a platform 156. A broadband source 160couples gateways 162 ₁, 162 ₂ and 162 _(N) with a WAN. The combinationsof intra-apartment networks 152 ₁, 152 ₂ and 152 ₃, telephone wires 164₁, 164 ₂ and 164 _(N) and gateways 162 ₁, 162 ₂ and 162 _(N) form LANs155 ₁, 155 ₂ and 155 _(N), similarly as in apartment building network100 of FIG. 2.

Gateways 162 ₁, 162 ₂ and 162 _(N) are coupled there between via asynchronicity link 166. It is noted that synchronicity link 166 may bewired or wireless. Gateway 162 ₁ operates as a master gateway to therest of the gateways, which operate as slave gateways (i.e., gateway 162₁ controls when the other gateways, and the nodes of their respectiveLANs, transmit data signals). Gateway 162 ₁ synchronizes the LANs totransmit upstream, downstream and HN data signals in synchrony, as shallbe described in further detail with reference to FIGS. 5A and 5B.

Reference is now made to FIG. 4, which is a schematic illustration of anapartment building network, constructed and operative in accordance witha further embodiment of the disclosed technique. Apartment buildingnetwork 170 includes intra-apartment networks APT₁ (referenced 152 ₁),APT₂ (referenced 152 ₂) and APT_(N) (referenced 152 _(N)), gateways G₁(referenced 162 ₁), G₂ (referenced 162 ₂) and G_(N) (referenced 162_(N)), and telephone wires 164 ₁, 164 ₂ and 164 _(N). A telephone wirebinder 188 runs from a basement 184 to the vicinity of intra-apartmentnetworks 182 ₁, 182 ₂ and 182 ₃. Gateways 192 ₁, 192 ₂ and 192 _(N) aremounted on a platform 186. A broadband source 190 couples gateways 192₁, 192 ₂ and 192 _(N) with a WAN. The combinations of intra-apartmentnetworks 182 ₁, 182 ₂ and 182 ₃, telephone wires 194 ₁, 194 ₂ and 194_(N) and gateways 192 ₁, 192 ₂ and 192 _(N) form LANs 185 ₁, 185 ₂ and185 _(N), similarly as in apartment building network 100 of FIG. 2.However, gateway 192 ₁ does not operate as the master node of LAN 185 ₁.Rather, a node 194 of intra-apartment network 182 ₁ is the LAN-masternode of LAN 185 ₁.

LAN-master node 194 and gateways 192 ₂ and 192 _(N) are coupled therebetween via a synchronicity link 196. Gateway 192 _(N) operates as amaster gateway to the rest of the LANs, similarly as gateway 162 ₁.However, gateway 192 _(N) synchronizes LAN 185 ₁ through LAN-master node194 (and not through gateway 192 ₁).

It is noted that alternatively, LAN-master node 194 may be linkeddirectly to master gateway 192 _(N). Further alternatively, asynchronizer such as synchronizer 126 of FIG. 2, may be applied to anapartment building network similar to apartment building network 170.Accordingly, LAN-master 194 is coupled with that synchronizer. It isfurther noted that the disclosed technique may similarly be applied toan MxU network wherein a plurality of LAN-master nodes are not gateways.

Reference is now made to FIG. 5A, which is a schematic illustration of atimeslot scheme sequence 200, constructed in accordance with anotherembodiment of the disclosed technique. Sequence 200 includes cyclictimeslot schemes, of which two schemes 202 and 206 are shown. Timeslotscheme 202 includes timeslots 204 ₁ and 204 ₂. Timeslot scheme 206includes timeslots 208 ₁ and 208 ₂. Timeslots 204 ₁ and 208 ₁, areallocated for downstream communication. Timeslots 204 ₂ and 208 ₂, areallocated for upstream communication and HN communication.

In the example set forth in FIG. 2, synchronizer 126 instructs gateways122 ₁, 122 ₂ and 122 _(N) and the nodes of their respective LANs thattimeslots 204 ₁ and 208 ₁ are allocated for downstream communicationonly. Accordingly, only gateways 122 ₁, 122 ₂ and 122 _(N) shall be ableto transmit signals within their respective LANs 115 ₁, 115 ₂ and 115_(N), during timeslots 204 ₁ and 208 ₁. Synchronizer 126 furtherinstructs gateways 122 ₁, 122 ₂ and 122 _(N) and the nodes of theirrespective LANs, that timeslots 204 ₂ and 208 ₂ are allocated forupstream and HN communication only. Accordingly, only the nodes ofintra-apartment networks 112 ₁, 112 ₂ and 112 _(N) shall be able totransmit signals within their respective LANs 115 ₁, 115 ₂ and 115 _(N),during timeslots 204 ₂ and 208 ₂.

For example, synchronizer 126 of FIG. 2 may include a clock (also knownas a sync clock), which is coupled with the LAN-master nodes. TheLAN-master nodes transmit data only during a certain part of the clockcycle (e.g., during the high level period of the cycle). Thus, theLAN-master nodes are synchronized with the clock, and hence aresynchronized there between.

It is noted that the timeslot scheme may be determined dynamically.Accordingly, the timeslot scheme may change according to the conditionspresent in MxU network 100, such as the bandwidth used by each networknode or LAN, the amount of upstream, downstream and HN communication,and the like. It is further noted that various other timeslot schemesmay be employed, such as a timeslot scheme allocating separate timeslotfor each LAN or group of LANs, a timeslot scheme involving only thoseLANs found interfering, and the like.

Reference is now made to FIG. 5B, which is a schematic illustration of atimeslot scheme sequence 210, constructed in accordance with a furtherembodiment of the disclosed technique. Sequence 210 includes repeatingtimeslot schemes, of which two schemes 212 and 216 are shown. Timeslotscheme 212 includes timeslots 214 ₁, 214 ₂ and 214 ₃. Timeslot scheme216 includes timeslots 218 ₁, 218 ₂ and 218 ₃. Timeslots 214 ₁ and 218₁, are allocated for downstream communication. Timeslots 214 ₂ and 218₂, are allocated for upstream communication and HN communication (alsoreferred to as upstream+HN). Timeslots 214 ₃ and 218 ₃ are allocated forother communication.

In the example set forth in FIG. 2, during timeslots 214 ₃ and 218 ₃,synchronizer 126 instructs gateways 122 ₁, 122 ₂ and 122 _(N) and thenodes of their respective LANs, not to generate upstream, downstream, orHN data signals. For example, timeslot 214 ₃ may be used forcommunication through the network, using a different communicationspecification, as shall be described with reference to FIG. 6C.

Reference is now made to FIG. 5C, which is a schematic illustration of atimeslot scheme sequence 220, constructed in accordance with anotherembodiment of the disclosed technique. Scheme sequence 220 includestimeslots 222 and 224. Timeslot 222 includes transmission opportunity(TXOP) 225 and gap 226. Timeslot 224 includes TXOPs 227 ₁, 227 ₂ and 227₃, and gap 228.

Timeslot 222 is similar to timeslot 204 ₁ of FIG. 5A, allocated fordownstream communication. Timeslot 224 is similar to timeslot 204 ₂(FIG. 5A), allocated for upstream+HN communication. TXOP 225 isallocated for the transmission of a specific data packet or packets, inthe downstream direction. Gap 226 separates between TXOP 225 and TXOP227 ₁. Each of TXOP 227 ₁, 227 ₂ and 227 ₃ is allocated for specificupstream or HN transmission, such as a specific data stream or aspecific network node or group of nodes. Gap 228 separates between TXOP227 ₃ and the next timeslot scheme (i.e., the next cycle). It is notedthat a system according to the disclosed technique may generally operateusing different types of TXOPs and gaps, such as those described in U.S.patent application Ser. No. 10/127,693, which is hereby incorporated byreference.

Reference is now made to FIGS. 6A, 6B and 6C. FIG. 6A is an illustrationin detail of intra-apartment networks 112 ₁ and 112 ₂ of FIG. 2, and aportion of the binder 118, operating during a downstream timeslot suchas timeslot 204 ₁ of FIG. 5A, in accordance with a further embodiment ofthe disclosed technique. FIG. 6B is an illustration in detail ofintra-apartment networks 112 ₁ and 112 ₂ of FIG. 2, and a portion of thebinder 118, operating during an upstream+HN timeslot such as timeslot204 ₂ of FIG. 5A, in accordance with another embodiment of the disclosedtechnique. FIG. 6C is an illustration in detail of intra-apartmentnetworks 112 ₁ and 112 ₂ of FIG. 2, and a portion of the binder 118,operating during an “miscellaneous” timeslot such as timeslot 214 ₃ ofFIG. 5B, in accordance with a further embodiment of the disclosedtechnique.

Intra-apartment network 112 ₁ includes network nodes 230 ₁, 230 ₂ and230 ₃. Intra-apartment network 112 ₂ includes network nodes 232 ₁, 232₂, 232 ₃ and 232 ₄. Nodes 232 ₁, 232 ₂, 232 ₃ and 232 ₄ are coupledthere between via telephone wire 124 ₂. It is noted intra-apartmentnetworks 112 ₁ and 112 ₂ may further include various other elements,such as additional nodes and wires, switches, and the like.

Each of network nodes 230 ₁, 230 ₂, 230 ₃, 232 ₁, 232 ₂, 232 ₃ and 232 ₄may be any point in the network which can transmit and receive data,such as a computer, a printer, an intercom, a digital telephone, anelectrical appliance, and the like. Nodes 230 ₁, 230 ₂, 230 ₃, 232 ₂,and 232 ₃ transmit and receive data according to a single, synchronous,predetermined first communication specification, such as HPNA3. Nodes230 ₁, 230 ₂, 230 ₃, 232 ₂, and 232 ₃ may operate according to asynchronous Media Access Control (MAC) as described in the abovementioned U.S. patent application Ser. No. 10/127,693.

Node 232 ₄ transmits and receives data according to a secondcommunication specification, such as HPNA2. It is noted that the secondcommunication specification may be either synchronous or asynchronous.Node 232 ₁ is capable of transmitting and receiving data signals of boththe first and the second communication specification.

With reference to FIG. 6A, gateway 1221 transmits a data signal 234through telephone wire 124 ₁, toward node 230 ₃ of intra-apartmentnetwork 112 ₁. Simultaneously, gateway 122 ₂ transmits another datasignal 236 toward node 232 ₂ of intra-apartment network 112 ₂.

With reference to FIG. 6B, node 230 ₁ of intra-apartment network 112 ₁transmits a first data signal 250 through telephone wire 124 ₁, towardnode 230 ₂. Node 230 ₂ of intra-apartment network 112 ₁ transmits asecond data signal 252 through telephone wire 124 ₁, toward gateway 122₁. Node 232 ₂ of intra-apartment network 112 ₂ transmits a third datasignal 254 through telephone wire 124 ₂, toward node 232 ₃. Node 232 ₂of intra-apartment network 112 ₂ transmits a fourth data signal 256through telephone wire 124 ₂, toward gateway 122 ₂. Data signals 250 and252 are transmitted synchronously, within LAN 115 ₁ (FIG. 2), during atleast one upstream+HN timeslot. Similarly, data signals 254 and 256 aretransmitted synchronously, within LAN 115 ₂ (FIG. 2), during at leastone upstream+HN timeslot. With reference to FIG. 6C, network node 232 ₄transmits a data signal 270 through telephone wire 124 ₂ to network node232 ₁.

It is noted that synchronizer 126 (FIG. 2) may restrict network node 232₁ to transmit only during the miscellaneous timeslot, by creatingconditions in network 100, which enable network node 232 ₁ to transmitdata signals only during the miscellaneous timeslot. For example, HPNA2legacy units (i.e., nodes operating solely according to an oldercommunication specification, and not according to later communicationspecification such as HPNA3 units), detect the various properties of thenetwork (e.g., voltage, current, frequency spectrum) in order todetermine if other nodes are transmitting. An HPNA2 node can transmitsignals when it detects that no HPNA signal is being transmitted on thecommunication line. Hence, either the synchronizer (when directlycoupled with the LANs) or the LAN-master nodes, can apply theappropriate signals on the network to prevent legacy units transmitting,during the downstream timeslots and the upstream+HN timeslots.Similarly, during the miscellaneous timeslot, either the synchronizer orthe LAN-master nodes, can instruct the advanced (non-legacy) nodes, notto produce HPNA signals on the communication line, thereby allowinglegacy units to transmit.

Reference is now made to FIG. 7, which is a schematic illustration of amethod for reducing NEXT in an MxU network, operative in accordance withanother embodiment of the disclosed technique. In procedure 300, atimeslot scheme is defined. The timeslot scheme includes a plurality oftimeslots, each being allocated for a selected type of signaltransmission (i.e., upstream, downstream, HN, miscellaneous, or acertain combination thereof). In the example set forth in FIGS. 2, 5Aand 5B, a timeslot scheme such as 204 ₁ or 214 ₁ is either embedded insynchronizer 116 or defined in real-time thereby. It is noted thatalternatively, other sources may define the timeslot scheme, such as anode of MxU network 100, an external node of the WAN, a user of MxUnetwork 100, and the like. In the example set forth in FIG. 5A, timeslot204 ₁ is allocated for downstream transmission, and timeslot 204 ₂ isallocated for upstream and HN transmission.

In procedure 302, MxU LAN-masters are synchronized according to thetimeslot scheme. The synchronization causes the nodes in each of theLANs to operate as defined in the timeslot scheme. With reference toFIG. 2, synchronizer 116 instructs each one of the LAN-master nodes ofMxU network 100 to regulate their respective LANs according to theselected timeslot scheme. Accordingly, gateways 122 ₁, 122 ₂ and 122_(N) are allowed to transmit upstream signals only during timeslot 204₁. Similarly, the nodes of intra-apartment networks 112 ₁, 112 ₂ and 112_(N) are allowed to transmit upstream+HN signals only during timeslot204 ₂.

In procedure 304, signals of a selected type are transmitted, duringeach of the respective timeslots. With reference to FIG. 2, gateways 122₁, 122 ₂ and 122 _(N) transmit upstream signals only during timeslot 204₁ and the nodes of intra-apartment networks 112 ₁, 112 ₂ and 112 _(N)transmit upstream+HN signals only during timeslot 204 ₂. It is notedthat procedure 304 is applied repetitively.

In procedure 306, conditions on the network are controlled, therebyenabling transmission of data signals of special types, such as legacycommunication signals. In the example set forth in FIGS. 2 and 5B,synchronizer 126 produces no HPNA signals on the MxU network, during thedownstream and upstream+HN timeslots, and an appropriate HPNA signalduring miscellaneous timeslot 214 ₃. The HPNA signal indicates to legacyunits that they are not allowed to transmit, as long as they detect it.

It is noted that procedure 306 is optional, and may be omitted incertain networks. For example, in a network comprising solely of nodesoperating according to a single communication specification (i.e.,non-legacy nodes), there may be no need to control the conditions on thenetwork. It is noted that when applying procedure 306, it has to beintegrated with procedure 304, so that both procedures are providedsimultaneously. Timeslot scheme 212 (FIG. 5B) is an example forintegrating both procedures 304 and 306.

It will be appreciated by persons skilled in the art that the disclosedtechnique is not limited to what has been particularly shown anddescribed hereinabove. Rather the scope of the disclosed technique isdefined only by the claims, which follow.

1-12. (canceled)
 13. Method of reducing NEXT (near end cross-talk) in anHPNA (Home Phoneline Networking Alliance) MxU (broadband, multi-user)network, the network comprising a plurality of LANs (local area network)each of the LANs comprising a LAN-master node, the method comprising theprocedures of: synchronizing said HPNA MxU network according to atimeslot scheme, said timeslot scheme comprising a plurality oftimeslots; and during each of said timeslots, transmitting data signalsof a selected type respective of said timeslot.
 14. The method accordingto claim 13, further comprising the preliminary procedure of definingsaid timeslot scheme, thereby allocating each of said plurality oftimeslots for said respective selected type.
 15. The method according toclaim 13, further comprising the procedure of controlling conditions onsaid HPNA MxU network during each of said timeslots, thereby enablingtransmission of data signals of said respective selected type. 16-18.(canceled)